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The regulatory mechanisms underlying the co-contraction of the biceps and triceps brachii muscles during elbow flexion remain unclear. This study aimed to elucidate the structural connections between nerve cells responsible for this co-activation. We employed the modified Sihler's staining technique to visualize the nerve-dense regions within the biceps and triceps brachii muscles. Additionally, a retrograde tracer (pseudorabies virus) expressing enhanced green and red fluorescent proteins was injected into these regions to map the structural relationships of nerve cells in the spinal cord, red nucleus of the midbrain, and the M1 region of the cerebral cortex. The nerve-dense regions in the biceps and triceps brachii muscles were located at 74.75 % and 61.90 % of muscle length, respectively. Three days post-injection, we observed single-labeled motor neurons innervating the biceps (green) and triceps (red), as well as double-labeled interneurons in the anterior horn of the spinal cord. Six days after injection, single- and double-labeled neurons were identified in the red nucleus and the M1 cortex. The presence of double-labeled neurons in both the spinal cord and brain regions provides evidence for the neural basis of co-activation in flexor and extensor muscles during elbow flexion. This study advances our understanding of the neural mechanisms controlling muscle co-contraction. [ABSTRACT FROM AUTHOR]

The purpose of the present study was to elucidate whether an external reference frame contributes to tactile localization in blindfolded healthy humans. In a session, the right forearm was passively moved until the elbow finally reached to the target angle, and participants reached the left index finger to the right middle fingertip. The locus of the right middle fingertip indicated by the participants deviated in the direction of the elbow extension when vibration was provided to the biceps brachii muscle during the passive movement. This finding indicates that proprioception contributes to the identification of the spatial coordinate of the specific body part in an external reference frame. In another session, the tactile stimulus was provided to the dorsal of the right hand during the passive movement, and the participants reached the left index finger to the spatial locus at which the tactile stimulus was provided. Vibration to the biceps brachii muscle did not change the perceived locus of the tactile stimulus indicated by the left index finger. This finding indicates that an external reference frame does not contribute to tactile localization during the passive movement. Humans may estimate the spatial coordinate of the tactile stimulus based on the time between the movement onset and the time at which the tactile stimulus is provided. [ABSTRACT FROM AUTHOR]

The kinesthetic illusion (KI) is a phenomenon in which transcutaneous vibration stimulation applied to a tendon induces the illusion of body movement. This phenomenon has potential applications in rehabilitation and virtual reality (VR). To effectively apply KI, precise vibration stimulation parameters (such as sine wave vibration with controlled frequency, acceleration, and pressing force against the tendon) must be delivered to various body parts. Thus, to realize this phenomenon, miniature vibrators must be developed and controlled. In this study, we developed a compact vibrator using a miniature voice coil motor to induce KI. We constructed a control system to regulate the target acceleration even in the presence of variations in the reactive forces from the tendon. Using the developed vibrator, we applied KI to the biceps brachii tendon and determined the optimal vibration stimulation conditions. The results revealed that the optimal vibration stimulation conditions for each subject’s biceps brachii muscle were related to the thickness of the upper arm. This result demonstrates the ability to determine guidelines for optimal stimulation conditions based on the physical characteristics of each individual participant. The increased ease of experiencing KI is expected to pave the way for rehabilitation using vibrators in wearable robots.

The distal rupture of the biceps brachii muscle tendon (DBT) accounts for 3% of biceps ruptures. Diagnosis typically relies on high clinical suspicion and complementary imaging studies, with >90% of cases documented in males between the fourth and sixth decades of life. Reports of DBT ruptures in females are scarce, mostly involving partial and degenerative injuries. Here, we present an unprecedented case of a 28-year-old female professional mixed martial arts athlete with a total traumatic DBT rupture. The athlete underwent surgical repair using anchor reattachment technique. No complications were observed, and the athlete showed satisfactory outcomes, being cleared for physiotherapy after 2 weeks and returning to sports after a 3-month postoperative period. [ABSTRACT FROM AUTHOR]

Introduction: The biceps brachii (BB) muscle is a two-headed muscle of the arm composed of one long head (LH) and one short head (SH). Accessory heads have been described and classified; however, reports of three concurrent accessory heads are especially rare, and their structural and functional analyses still require investigation. This study aims to analyze the structural and functional properties of a bilateral case of BB muscles each with three accessory heads. Methods: A case of bilateral BB muscles with three accessory heads were discovered during routine human cadaver dissection. The muscles were carefully cleaned of extraneous tissue and photographed in situ. All five heads were examined bilaterally for gross structural features, and sarcomere states were examined via light microscopy. Maximal isometric force (Fmax) and contralateral comparability (δ) were calculated for each head. Results: The three accessory heads originated sequentially from the mid-shaft of the humerus. The proximal accessory head inserted into the distal end of the SH, while the middle and distal accessory heads inserted separately into the adjoined LH and SH muscle mass just before the common tendon. All accessory heads were structurally similar (δ ≤ 0.17; mass = 2.10 g; length = 10.33 cm; PCSA = 0.23 cm2; Fmax = 5.24 N) and were innervated by the musculocutaneous nerve. The left and right LH and SH collectively generated a Fmax of 49.91 N and 53.05 N while the left and right accessory heads collectively generated a Fmax of 18.04 N and 13.38 N, respectively. Conclusions: The bilateral BB muscles with their accessory heads generated an almost equivalent total Fmax (67.95 N vs. 66.43 N, respectively), ∼23.35% of which was generated by the accessory heads. Despite the conceivable advantage the accessory heads may offer to generating additional force, accessory muscles can also cause serious clinical implications. The gross imaging, biomechanical analyses, contralateral comparability data, and relevant clinical insights presented in this study may help guide diagnosis and treatment in related clinical cases.

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Distal biceps tendon rupture is most commonly found in working-age men, making the treatment terms and functional recovery level of significant socio-economic importance. Modern scientific research aims to minimize the number of complications, particularly recurrent ruptures. Attention is drawn to modern technologies aimed at stimulating regenerative processes, including the use of the stromal vascular fraction (SVF) of abdominal adipose tissue. The article presents the results of the practical application of SVF in the surgical restoration of the distal biceps tendon of the shoulder. The aim of the study: to improve the results of surgical treatment of distal biceps tendon rupture, shorten recovery times and reduce the incidence of complications using stromal vascular fraction obtained from adipose tissue. Materials and methods. The study was carried out by evaluating the results of surgical restoration of the distal biceps tendon in 34 patients who were divided into 2 groups – with intraoperative introduction of SVF at the reattachment site (n = 14) and without it (n = 20). At follow-up examinations after 3 days, 2 weeks, 6 weeks, and 3 months, the results of the patients were evaluated using the VASH, DASH scales and the range of motion in the affected elbow joint was measured. In addition, a general blood analysis and quantitative determination of C-reactive protein were performed before the operation and at follow-up visits. Results. There was no difference in the level of C-reactive protein and the general blood analysis score between patients in both groups at all study time points. It was found that after 2 weeks, the VAS score was significantly lower in the study group. The DASH score on follow-up examinations after 2 and 6 weeks was significantly better in the study group. Also, at follow-up examinations after 2 and 6 weeks, a greater volume of supination movements was observed in the study group. Conclusions. The using of SVF did not lead to the development of postoperative complications. The using of SVF allowed the reduction of the recovery time and decreased in the incidence of complications, as well as improved functional outcomes.

Abstract Background To achieve different central preset force levels requires various fine-tuning efforts and may elicit different uptight responses. The mandibular lever system has a distinct regularity in the fine-tuning function of the upper limbs. The purpose of the present study was to detect whether the uptight responses elicited from motivating clenching differ from those induced by motivating forearm raising at different force levels. Methods Twenty-five healthy females were enrolled in this study. The target was low, medium, and maximum force levels with or without visual feedback and/or maintenance effort. Surface electromyographic (SEMG) activity was recorded from the bilateral anterior temporalis and masseter or left biceps brachii muscle (BicL), and the T-Scan III System synchronously recorded the sensitive force values. The uptight responses and task difficulties were recorded for occlusal and left forearm lifting tasks using a unique visual analogue scale. Results The highest uptight response value was achieved at a low clenching force level with visual feedback requiring no maintenance effort but at a maximum forearm-raising force level with visual feedback and maintenance effort. The SEMG activities of both jaw-closing muscles and BicL were associated with the central preset force level (P

Background: Resistance exercise can be defined as the percentage of maximal strength (%1 repetition maximum) used for a particular exercise. Shear wave elastography (SWE) is a robust and novelty imaging technique that provides information regarding tissue stiffness. Superb microvascular imaging (SMI) is a non-irradiating technique that can provide quantitative measurement of muscle blood flow non-invasively. Purpose: To compare the acute effects of low- and high-velocity resistance exercise on stiffness and blood flow in the biceps brachii muscle (BBM) using SWE and SMI. Material and Methods: This prospective study included 60 healthy men (mean age=28.9 years; age range=26–34 years). BBM stiffness was measured by using SWE at rest, after low- and high-velocity resistance exercise, and muscle blood flow was also evaluated by SMI. Resistance exercise was performed using a dumbbell with a mass adjusted to 70%–80% of one-repetition maximum. Results: The stiffness values increased significantly from resting to high- and low-velocity resistance exercises. There was no significant difference between the elastography values of the BBM after the high- and low-velocity resistance exercise. The blood flow increased significantly from resting to high- and low-velocity resistance exercises. Blood flow increase after low-velocity exercise was significantly higher compared to high-velocity exercise. Conclusion: While muscle stiffness parameters and blood flow significantly increased from resting after both high- and low-velocity resistance exercises, blood flow significantly increased after low-velocity exercise compared to high-velocity exercise. This can mean that metabolic stress, an important trigger for muscle development, is more likely to occur in low-velocity exercise. [ABSTRACT FROM AUTHOR]

Background: To achieve different central preset force levels requires various fine-tuning efforts and may elicit different uptight responses. The mandibular lever system has a distinct regularity in the fine-tuning function of the upper limbs. The purpose of the present study was to detect whether the uptight responses elicited from motivating clenching differ from those induced by motivating forearm raising at different force levels. Methods: Twenty-five healthy females were enrolled in this study. The target was low, medium, and maximum force levels with or without visual feedback and/or maintenance effort. Surface electromyographic (SEMG) activity was recorded from the bilateral anterior temporalis and masseter or left biceps brachii muscle (BicL), and the T-Scan III System synchronously recorded the sensitive force values. The uptight responses and task difficulties were recorded for occlusal and left forearm lifting tasks using a unique visual analogue scale. Results: The highest uptight response value was achieved at a low clenching force level with visual feedback requiring no maintenance effort but at a maximum forearm-raising force level with visual feedback and maintenance effort. The SEMG activities of both jaw-closing muscles and BicL were associated with the central preset force level (P < 0.001). However, the maintenance effort only increased the jaw-closing muscles' SEMG activity at the maximal force level (P < 0.001). Conclusions: Clenching at the central preset lower force level with visual feedback is prone to elicit a higher degree of uptight response. The constant need for a low-intensity bite can have a negative effect on an individual's mood. [ABSTRACT FROM AUTHOR]

The anatomy of the biceps brachii muscle has been a subject of interest to many researchers. In particular, the presence of one or more accessory heads has been reported to be the most common variation of the biceps brachii muscle. In fact, contemporary knowledge is quite inconsistent and lacks a definitive summary. Taking this into account, the present study aims to investigate the overall prevalence of the accessory heads and related questions, such as their broad morphological features, population variance, sexual dimorphism, side distribution or the changes in prevalence rates over time. A literature search of major scientific databases was conducted and produced 78 eligible articles, including 10,603 upper limbs, for our study. Relevant data were extracted and consequently analysed with the use of random‐effects meta‐analysis. As a result, the accessory heads occur with an overall prevalence of 9.6% (95% CI 8–11%) and by far the most common is the presence of a single accessory head (8.4%; 95% CI 7–10%). Additional sub‐analyses revealed that accessory heads appear more frequently unilaterally and in males. Differences between the occurrence on the right or left side were not significant. Moreover, a decreasing trend in prevalence rates over time was observed, pointing towards an evolutionary adaptation. The innervation and blood supply of the accessory heads are nearly identical to that of the normal biceps brachii muscle. Although the accessory heads are usually asymptomatic, their potential presence must be kept in mind while interpreting various conditions. In addition, their direct clinical importance is speculated and is thought that they might be conductive to several pathological processes around the shoulder girdle and brachial region. While many of the morphological and morphometric aspects of the accessory heads are well documented, their functional value is still a matter for future investigations. [ABSTRACT FROM AUTHOR]

Anatomic variation of the biceps brachii muscle (BBM) is frequently observed; its pattern is diverse and clinically important. During the educational dissection of a 78-year-old Korean male cadaver, six additional asymmetrical heads of the biceps brachii muscle (BBM) were found on both sides. On the right side, two additional heads originated from the humerus; the musculocutaneous nerve passed between these heads and the short head of the BBM. Four additional heads were found on the left side, anterior to the BBM, one of which originated from the pectoralis major muscle. Posterior to the BBM, two heads of tendons originated from the coracobrachialis muscle and one head of the muscle belly originated from the humerus. The left musculocutaneous nerve pierced the coracobrachialis muscle and continued distally passing between the short head of the BBM and the additional heads located posterior to the BBM. It then gave off the variant musculocutaneous nerve to the median nerve. On both sides, the short and long heads of the BBM had normal origins, insertions, and courses. This novel variation has various clinical and embryological implications. [ABSTRACT FROM AUTHOR]

Effects of low-threshold afferents from the anterior (DA), middle (DM) and posterior parts of the deltoid (DP) on the excitability of biceps brachii (BB) motoneurons in humans were studied. We evaluated the effects on individual motor units and motoneuron pool using a post-stimulus time-histogram (PSTH) and an electromyogram-averaging (EMG-A) methods, respectively, in 11 healthy human subjects. Electrical conditioning stimulation was delivered to the axillary nerve branch innervating DA (DA nerve), DM (DM nerve) and DP (DP nerve) with the intensity below the motor threshold. In the PSTH study, stimulation to the DA, DM and DP nerves produced a significant peak (facilitation) in 26/40 (65%), 28/47 (59%) and 0/32 (0%) of BB motor units, respectively. Since the central latency of the facilitation from the DA and DM nerves was 0.1 ± 0.3 and 0.1 ± 0.2 ms (mean ± S.D.) longer than that of the homonymous monosynaptic Ia facilitation of BB, respectively, the facilitation thus being compatible with monosynaptic path. In the EMG-A study, stimulation to the DA and DM nerves produced a significant peak (facilitation) for the BB motoneuron pool in all the subjects, whereas stimulation to the DP nerve produced no effect on BB. The facilitation diminished by vibration stimulation, and the suppression lasted for 30–40 min after removal of the vibration. Therefore, group Ia afferents should be responsible for the facilitation. These findings suggest that monosynaptic facilitation mediated by group Ia afferents from the DA and DM nerves to BB motoneurons exists in humans. [ABSTRACT FROM AUTHOR]

Muscle activities of the elbow flexors, especially the brachialis muscle (BR), have been measured with intramuscular electromyography (EMG) using the fine-wire electrodes. It remains unclear whether BR activity can be assessed using surface EMG. The purpose of this study was to compare the EMG patterns of the BR activity recorded during elbow flexion using surface and fine-wire electrodes and to determine whether surface EMG can accurately measure the BR activity. Six healthy men were asked to perform two tasks—a maximum isometric voluntary contractions (MVICs) task and an isotonic elbow-flexion task without lifting any weight. The surface and intramuscular EMG were simultaneously recorded from the BR and the long and short heads of the biceps brachii muscle (BBLH and BBSH, respectively). The locations of the muscles were identified and marked under ultrasonographic guidance. The peak cross-correlation coefficients between the EMG signals during the MVICs task were calculated. For the isotonic elbow-flexion task, the EMG patterns for activities of each muscle were compared between the surface and the fine-wire electrodes. All cross-correlation coefficients between the surface EMG signals from the muscles were lower than 0.3. Furthermore, the EMG patterns of the BR activity were not significantly different between the surface and the fine-wire electrodes. The BR has different EMG pattern from the BBLH and the BBSH. The BR activity, conventionally measured with intramuscular EMG, can be accurately accessed with surface EMG during elbow flexion performed without lifting any weight, independent from the BBLH and BBSH activities. [ABSTRACT FROM AUTHOR]

Daily and sports activities can be affected by joint injury. The objectives of physical therapy are to help patients regain range of motion (ROM), mobility, strength, and function. The purpose of this study was to examine the optimal joint range of elbow flexion and recommended training weight for the recovery of biceps brachii muscle strength. It was a prospective study with a sample of 157 healthy young adult volunteers from two institutions. The Hawk goniometer was used for measurements. Participants performed a flexion-extension movement of the elbow in standing, in series, with progressive loads. The ROM in males was found to be higher than in females. Nevertheless, the joint values of the dominant and non-dominant arm indicate that there are differences between both arms, regardless of gender. In relation to the force used during the performance of the activity, the weight used by the women was lower than that of the men, whereas, during the execution, women showed greater stability throughout the test, compared to men. Normative values have been established for the ROM and weights to be used in the recovery process of injuries to the long tendon of the biceps brachii muscle. [ABSTRACT FROM AUTHOR]

Muscle activities of the elbow flexors, especially the brachialis muscle (BR), have been measured with intramuscular electromyography (EMG) using the fine-wire electrodes. It remains unclear whether BR activity can be assessed using surface EMG. The purpose of this study was to compare the EMG patterns of the BR activity recorded during elbow flexion using surface and fine-wire electrodes and to determine whether surface EMG can accurately measure the BR activity. Six healthy men were asked to perform two tasks—a maximum isometric voluntary contractions (MVICs) task and an isotonic elbow-flexion task without lifting any weight. The surface and intramuscular EMG were simultaneously recorded from the BR and the long and short heads of the biceps brachii muscle (BBLH and BBSH, respectively). The locations of the muscles were identified and marked under ultrasonographic guidance. The peak cross-correlation coefficients between the EMG signals during the MVICs task were calculated. For the isotonic elbow-flexion task, the EMG patterns for activities of each muscle were compared between the surface and the fine-wire electrodes. All cross-correlation coefficients between the surface EMG signals from the muscles were lower than 0.3. Furthermore, the EMG patterns of the BR activity were not significantly different between the surface and the fine-wire electrodes. The BR has different EMG pattern from the BBLH and the BBSH. The BR activity, conventionally measured with intramuscular EMG, can be accurately accessed with surface EMG during elbow flexion performed without lifting any weight, independent from the BBLH and BBSH activities.

Purpose: Although variations of biceps brachii muscle (BBM) and arm arteries are common, however, combined bilateral variations involving muscles and arteries are rarely described. The report's aim was the detailed presentation of a case of bilateral multiple anatomical variations in the upper extremities encountered during the dissection of a 90-year-old Japanese female cadaver. Results: On the left side, a third (accessory) head of the (BBM) was observed. Interestingly, the bicipital aponeurosis was composed of two layers, a superficial layer and a deep one. Arterial variations involved the high division of the brachial artery into the brachioradial artery (BRA), running superficially to the median nerve and the ulno-interosseous trunk occupying a normal position of the typical brachial artery. On the right side, a four-headed BBM was observed. The bicipital aponeurosis was also composed of two layers (superficial and deep), similarly to the left side. On this side, the BRA took origin from the axillary artery and crossed over the median nerve's medial root. Then, the BRA descended along the median nerve. On both sides, the BRA passed between two layers of the bicipital aponeurosis and continued its course in the forearm as the radial artery. Conclusions: Knowledge about the co-existence of multiple variations on the arm is essential for clinicians performing surgical procedures, and for medical education.

Purpose: The lacertus fibrosus (LF) is involved in various surgeries. However, the biomechanical contribution of the LF remains unclear. The aim of this study was to determine the role of the lacertus fibrosus on the elbow and forearm kinematics and on the biceps brachii muscle lever arms. Methods: This biomechanical study was performed on seven fresh-frozen upper limbs of cadavers. Elbow flexion, forearm supination, and biceps brachii muscle lever arms were analyzed in the intact conditions (I) and after superficial (R) and deep part (R2) of the lacertus fibrosus release, respectively. Results: Elbow flexion shows a significant difference (p < 0.0001) between I, R, R2. Abduction/adduction shows a significant difference between I-R (p < 0.0001) and I-R2 (p < 0.0001). Supination does not show a significant difference in mean maximum amplitude, but between 40 and 70%, there are significant differences. There is a significant mean decrease of lever arm in flexion (28%) and supination (50%) after superficial and deep part of the lacertus fibrosus release. Conclusion: The results of this study show that the lacertus fibrosus increases the lever arm during flexion and supination. It limits the flexion and abduction of the elbow and supination of the forearm. Lacertus fibrosus maintains the rhythmicity between the elbow flexion and supination of the forearm. Level of evidence: Basic science study, biomechanics [ABSTRACT FROM AUTHOR]

The biceps brachii muscle is a highly variable muscle in the anterior compartment of the arm, and the most common variants include additional heads or slips. The median nerve courses with the brachial artery in the medial arm near the biceps brachii muscle, crosses the elbow, and enters the forearm deep to the bicipital aponeurosis. While entrapment of the median nerve in the carpal tunnel is one of the most common neuropathies, more proximal entrapments by the bicipital aponeurosis or other variants have been reported. In a 94-year-old embalmed female cadaver received through the Humanity Gift Registry of Pennsylvania, a biceps brachii muscle with an additional slip that arose from the coracoid process was found, which bridged over the median nerve and blended with the investing fascia of the forearm flexors via aponeurosis. Because of the course of this muscular slip in the arm and its relationship to the median nerve, this may be an additional site of proximal entrapment of the median nerve. It is important to consider these rare sites of nerve entrapment when diagnosing patients with median nerve neuropathy., Competing Interests: Human subjects: All authors have confirmed that this study did not involve human participants or tissue. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work., (Copyright © 2024, Kulesza et al.)

Daily and sports activities can be affected by joint injury. The objectives of physical therapy are to help patients regain range of motion (ROM), mobility, strength, and function. The purpose of this study was to examine the optimal joint range of elbow flexion and recommended training weight for the recovery of biceps brachii muscle strength. It was a prospective study with a sample of 157 healthy young adult volunteers from two institutions. The Hawk goniometer was used for measurements. Participants performed a flexion-extension movement of the elbow in standing, in series, with progressive loads. The ROM in males was found to be higher than in females. Nevertheless, the joint values of the dominant and non-dominant arm indicate that there are differences between both arms, regardless of gender. In relation to the force used during the performance of the activity, the weight used by the women was lower than that of the men, whereas, during the execution, women showed greater stability throughout the test, compared to men. Normative values have been established for the ROM and weights to be used in the recovery process of injuries to the long tendon of the biceps brachii muscle.

Up to now relatively little is known about interlimb reflexes (ILR). Especially it is not well known whether ILR may habituate or not to subsequent stimuli. The main aim of the present investigation was to explore the short term habituation behavior of ILR. The electromyogram was recorded over the tonically active biceps brachii (BB) muscle in 11 healthy subjects contralateral and ipsilateral to supramaximum electrical stimuli (9–12 mA) that were delivered at 1.0 and 0.4 Hz over the left sural nerve. In addition, a selective averaging method was used to investigate the influence of preceding stimuli on the ILR. Thus, 30 blocks of 3 subsequent stimuli were used. All 1st ILR of each block were averaged together. Averages were also obtained for 2nd and 3rd ILR. While ILR amplitudes gained significantly both ipsilateral and contralateral to the stimulus (p < 0.05) after train stimuli as compared with single stimuli, ILR amplitudes showed a significant decrease at 1.0 Hz versus 0.4 Hz stimuli. ILR amplitudes decreased significantly after the 2nd and 3rd stimulus relative to the 1st (p < 0.05). ILR can be recorded bilaterally remote from the stimulus site. Furthermore, ILR show clear short term habituation behavior.

Purpose: The aim of the study was to evaluate the reliability of ultrasound shear wave elastography (SWE) to assess biceps brachii muscle (BBM) and quadriceps muscle (QM) stiffness in senior volunteers. Methods: Using a linear array ultrasound transducer (7 MHz), we prospectively measured shear wave velocity (SWV) of BBM and QM in passive joints (elbow and knee) flexion (90°) and extension (180°) in 19 senior volunteers by two operators. We developed SWV rate (SWV elbow-extension – SWV elbow-flexion)/SWV elbow-flexion to assess BBM contractibility. Statistical analysis included unpaired t -test to examine the difference in SWV of muscle between left vs right limbs, men vs women, and athletes vs nonathletes; Intraclass correlation coefficient (ICC) and violin plots for analyzing intra- and inter-observer reliability in performing SWE in muscles. Results: There was no significant difference in SWV between left vs right (flexion or extension), male vs female (flexion or extension), for BBM and QM, and athlete vs nonathlete extension for QM (all p > 0.05). The difference in SWV of BBM in elbow extension and in SWV rate between athlete and nonathlete was significant (p < 0.05). The difference in muscle SWV between joint flexion and extension was also significant (p < 0.05). Reliability in performing SWE of BBM and QM was good (ICC > 0.75). Conclusions: Our results suggest that ultrasound SWE is feasible in estimating BBM and QM stiffness in seniors with good reproducibility. SWV rate and SWV of the extended BBM representing muscle contractibility in athlete were higher than in nonathlete. • Development of a new ultrasound parameter (shear wave velocity rate) for assessing muscle contractibility • Quantification of the difference in muscle stiffness and contractibility between athlete and nonathlete in seniors. • Good inter-observer and intra-observer variability in performing shear wave elastography of skeletal muscles [ABSTRACT FROM AUTHOR]

Up to now relatively little is known about interlimb reflexes (ILR). Especially it is not well known whether ILR may habituate or not to subsequent stimuli. The main aim of the present investigation was to explore the short term habituation behavior of ILR. The electromyogram was recorded over the tonically active biceps brachii (BB) muscle in 11 healthy subjects contralateral and ipsilateral to supramaximum electrical stimuli (9–12 mA) that were delivered at 1.0 and 0.4 Hz over the left sural nerve. In addition, a selective averaging method was used to investigate the influence of preceding stimuli on the ILR. Thus, 30 blocks of 3 subsequent stimuli were used. All 1st ILR of each block were averaged together. Averages were also obtained for 2nd and 3rd ILR. While ILR amplitudes gained significantly both ipsilateral and contralateral to the stimulus (p < 0.05) after train stimuli as compared with single stimuli, ILR amplitudes showed a significant decrease at 1.0 Hz versus 0.4 Hz stimuli. ILR amplitudes decreased significantly after the 2nd and 3rd stimulus relative to the 1st (p < 0.05). ILR can be recorded bilaterally remote from the stimulus site. Furthermore, ILR show clear short term habituation behavior. [ABSTRACT FROM AUTHOR]

Variation in the biceps brachii muscle is extremely frequent and has a clinical significance. During an educational dissection, third head of the biceps brachii muscle was found on the left side in a Korean cadaver The short and long heads showed normal morphology and course: however, additional head originated from the greater tubercle connected to long head of biceps brachii muscle and crossed the musculocutaneous nerve perpendicularly. And then, it was inserted into short head of the biceps brachii muscle. The author describes this previously novel case report and discusses the clinical implications of such a variant. [ABSTRACT FROM AUTHOR]

We prospectively investigated the feasibility of using quantitative ultrasound imaging (QUI) to assess the biceps brachii muscle (BBM) in individuals with chronic post-stroke spasticity. To quantify muscle echogenicity and stiffness, we measured QUI parameters (gray-scale pixel value and shear wave velocity [SWV, m/s]) of the BBM in three groups: 16 healthy BBMs; 12 post-stroke, non-spastic BBMs; and 12 post-stroke, spastic BBMs. The QUI results were compared with the Modified Ashworth Scale and Tardieu Scale. A total of 20 SWVs were measured in each BBM, once at elbow in 90° flexion and again at maximally achievable extension using acoustic radiation force impulse imaging. BBM pixel value was measured in gray-scale images captured at 90° elbow flexion using ImageJ software. Statistical analyses included analysis of variance for examining the difference in SWV and pixel values among the three groups; Bonferroni correction for testing the difference in SWV and pixel values in a paired group; t-test for examining the difference in SWV values measured at two elbow angles; and Pearson correlation coefficient for analyzing the correlation of QUI to Modified Ashworth Scale and Tardieu Scale. SWV significantly differed between spastic BBMs and non-spastic or healthy BBMs. For pixel values, each of the three groups significantly differed from the others at elbow 90° flexion. The difference in SWV measured between the two elbow angles was also significant (p <0.01). A strong negative correlation was found between SWV and passive range of motion (R2 = -0.88, p <0.0001) in spastic upper limbs. These results suggest that the use of QUI is feasible in quantitative assessment of spastic BBM. [ABSTRACT FROM AUTHOR]

Objectives: The aim of the study was to assess the feasibility of ultrasound strain imaging in characterizing the biceps brachii muscle in chronic poststroke spasticity. Methods: We prospectively analyzed strain imaging data from bilateral biceps brachii muscles in 8 healthy volunteers and 7 patients with poststroke chronic spasticity. Axial deformations of the biceps brachii muscle and overlying subcutaneous tissue were produced by external compression using a sandbag (1.0 kg) attached to a transducer. The lengthening and shortening of the biceps brachii muscle and subcutaneous tissue were produced by manual passive elbow extension (from 90° to 0°) and flexion (from 0° to 90°), respectively. We used offline 2‐dimensional speckle tracking to estimate axial and longitudinal strain ratios (biceps brachii strain/subcutaneous tissue strain), and the longitudinal tissue velocity of the biceps brachii muscle. Statistical analyses included analysis of variance for testing differences in strain imaging parameters among healthy, nonspastic, and spastic biceps brachii muscles, the Bonferroni correction for further testing differences in US strain imaging among paired groups (healthy versus spastic, nonspastic versus spastic, and healthy versus nonspastic), and the Pearson correlation coefficient for assessing the intraobserver reliability of performing strain imaging in stroke survivors. Results: The differences in strain imaging parameters between healthy and spastic and between nonspastic and spastic biceps brachii muscles were significant at both 90° elbow flexion and maximal elbow extension (P < .01). There was no significant difference in axial strain ratios at 90° of elbow flexion or longitudinal tissue velocities between healthy and nonspastic muscles (P > .05). The intraobserver reliability of performing strain imaging in stroke survivors was good (r = 0.85; P < .01). Conclusions: Ultrasound strain imaging seems to be feasible for characterizing the biceps brachii muscle in chronic poststroke spasticity. [ABSTRACT FROM AUTHOR]

Lack of knowledge of variations in human morphology and their magnitude compared to normal anatomy may have significant clinical consequences. Accurate knowledge of anatomical variations provides important information in medico-legal issues, forensic interpretation, diagnostics, imaging and patient management including surgical procedures. Although underreported, it is believed that a significant proportion of clinical malpractice is due to suboptimal knowledge of anatomical variations. The present study aims to assess the anatomical variations of locomotor system structures in twenty-four formalin fixed cadavers used for dissection as part of Gross Anatomy course for medical students. The study was conducted in six medical schools in Ethiopia in the academic year 2015/2016. Following critical observation and careful dissection, photographs were taken accordingly. Our findings show a complete persistence of metopic suture in 4.2 % of frontal bone, incedence of five anterior and five posterior sacral foramina in 4.2 % of sacral bones and biceps brachii muscle with three heads of origin in 2.1 % of brachia. Altogether, the findings show the incidence of anatomical variants of clinical importance that need consideration during surgical procedures, diagnosis - especially in distinguishing fracture of bones - and patient management in Ethiopian population with diverse socio- economic background and geographical origin. [ABSTRACT FROM AUTHOR]

Background: Biceps augmentation using solid silicone implants has been increasingly requested in recent years despite a paucity of literature evaluating the safety and efficacy of this procedure.Objectives: The purpose of this study was to provide information about complications, surgical planning, and aesthetic outcomes of biceps augmentation.Methods: A retrospective chart review was conducted for patients undergoing solid silicone biceps augmentation in the author's practice from April 2011 through May 2016. Collected data were analyzed to assess the indications for surgery, quantity of complications, and need for surgical revision, and to evaluate aesthetic outcome.Results: Twenty-one male patients were included in the study. The mean age was 42.6 years and the mean follow up was 7.1 months. Indications for surgery include a desire to increase biceps size (n = 16), and correction of biceps deformity after biceps tendon rupture (n = 5). Eight patients underwent subfascial implant placement and 13 submuscular implant placement. Complications occurred in 10 patients (48%) including asymmetry (n = 4), seroma (n = 3), surgical site infection (SSI) (n = 1), cellulitis (n = 1), and hematoma (n = 1). The overall reoperation rate was 23.8%. Implant malposition occurred in 3 of the 8 (38%) of subfascial implant placement patients. Complications requiring revision surgery were higher for subfascial implants 37.5% vs 15.4% for submuscular.Conclusions: Biceps augmentation with a solid silicone implant can increase upper arm volume and correct asymmetry and deformity resulting from muscle injury. Submuscular biceps implant placement is recommended over subfascial insertion to avoid implant malposition.Level Of Evidence4: [ABSTRACT FROM AUTHOR]

The anatomical variations of the biceps brachii muscle in relation to the number of supernumerary or accessory bellies may have important incidence in clinical and radiological diagnoses, as well as in surgical procedures. The absence of an appropriate classification for the variations that the biceps brachii muscle can present and the findings of the present study, allowed the authors to present a classification proposal based on the number of accessory bellies and their origin. The study aimed to determine with which frequency the variations in the number of accessory bellies of the biceps brachii muscle are present, and to propose a classification for these variations. In the crosssectional, descriptive study 90 arms of 46 Colombian cadavers were analyzed. A high frequency (19.6%) in the variations of the muscle was found, 4.3% bilaterally and 15.2% unilaterally. In the 11 arms (12.2%) that presented the variation, the presence of only one accessory belly was the highest frequency (81.8%), being the most frequent origin for them the one classified by the authors as 3b, 3 for the inferomedial situation and b for the interval between the insertion of the coracobrachii muscle and the origin of the brachii muscle. Because the classification proposed is very detailed, its use is recommended whenever cases of biceps brachii muscle variations are reported. In the cadavers of the Colombian population studied, a high frequency was found for the presence of supernumerary or accessory heads of this muscle, which deserves to be known by medical professionals. [ABSTRACT FROM AUTHOR]

Noninvasive techniques, surface electromyography (sEMG) in particular, are being increasingly employed for assessing muscle activity. In these studies, local oxygen consumption and muscle metabolism are of great interest. Measurements can be performed noninvasively using optics-based methods such as near-infrared spectroscopy (NIRS). By combining energy consumption data provided by NIRS with muscle level activation data from sEMG, we may gain an insight into the metabolic and functional characteristics of muscle tissue. However, muscle motion may induce artifacts into EMG and NIRS. Thus, the inclusion of simultaneous motion measurements using accelerometers (ACMs) enhances possibilities to perceive the effects of motion on NIRS and EMG signals. This paper reviews the current state of noninvasive EMG and NIRS-based methods used to study muscle function. In addition, we built a combined sEMG/NIRS/ACM sensor to perform simultaneous measurements for static and dynamic exercises of a biceps brachii muscle. Further, we discuss the effect of muscle motion in response of NIRS and EMG when measured noninvasively. Based on our preliminary studies, both NIRS and EMG supply specific information on muscle activation, but their signal responses also showed similarities with acceleration signals which, in this case, were supposed to be solely sensitive to motions.

Purpose: We established a detailed sonographic approach to the bicipital aponeurosis (BA), because different pathologies of this, sometimes underestimated, structure are associated with vascular, neural and muscular lesions; emphasizing its further implementation in routine clinical examinations. Methods: The BA of 100 volunteers, in sitting position with the elbow lying on a suitable table, was investigated. Patients were aged between 18 and 28 with no history of distal biceps injury. Examination was performed using an 18-6 MHz linear transducer (LA435; system MyLab25 by Esaote, Genoa, Italy) utilizing the highest frequency, scanned in two planes (longitudinal and transverse view). In each proband, scanning was done with and without isometric contraction of the biceps brachii muscle. Results: The BA was characterized by two clearly distinguishable white lines enveloping a hypoechoic band. In all longitudinal images (plane 1), the lacertus fibrosus was clearly seen arising from the biceps muscle belly, the biceps tendon or the myotendinous junction, respectively. In transverse images (plane 2) the BA spanned the brachial artery and the median nerve in all subjects. In almost all probands (97/100), the BA was best distinguishable during isometric contraction of the biceps muscle. Conclusion: With the described sonographic approach, it should be feasible to detect alterations and unusual ruptures of the BA. Therefore, we suggest additional BA scanning during clinical examinations of several pathologies, not only for BA augmentation procedures in distal biceps tendon tears. [ABSTRACT FROM AUTHOR]